Tissue repair using a bone graft material is performed on bone defects of long bones, cervical vertebrae, skull bones, etc. In regard to material quality, the bone graft material is required to have excellent biocompatibility and osteoconductive ability. A calcium phosphate-based ceramic, etc., such as hydroxyapatite (hereinafter abbreviated as “HAp”), etc., is often used as such a material. However, when such a ceramic is used in a form of a bulky, massive formed object, there is a problem that a central portion is high in probability of infection. A binder, such as gelatin, etc., is thus used (see, for example, Patent Document 1).
Also, tooth decay bacteria attaches to a dental surface to form plaque and the tooth decay bacteria, which thereby initiates dental caries, metabolizes foodstuffs inside the plaque to produce an acid that dissolves calcium and phosphorus immediately below the dental surface, thereby decalcifying dental enamel and forming an incipient caries state. As substances that promote recalcification, HAp and other calcium phosphate-based ceramics, etc., are known. However, HAp, etc., are poor in solubility in water and poor in adhesion to teeth, and thus a sufficient effect cannot be obtained by a means, such as coating, etc.
Therefore, for example, a dental adhesive film having HAp, etc., dispersed in a water-soluble or swelling supporting substance that adheres to teeth is used (see, for example, Patent Document 2) or electromagnetic waves are irradiated on a dental surface coated with a coating agent containing HAp to grow HAp crystals on the dental surface (see, for example, Patent Document 3).
However, with the films described in Patent Documents 1 and 2, fixing onto hard tissue is difficult to achieve because a fixing force of gelatin, etc., is not sufficient. Also the method of Patent Document 3 cannot be implemented easily because a coating agent irradiating apparatus is required.
Further, the conventionally available hard tissue restoration materials are mainly purported for hard tissue repair of a hard tissue defect, etc., and cannot restore tissue in a periphery of a bone or tooth, for example, periodontal tissue (alveolar bone, periodontal membrane, cementum, and gum) in a case of a tooth.
In addition, whitening, with which teeth are bleached by a bleaching chemical, such as hydrogen peroxide, urea peroxide, etc., is performed to make teeth appear white. However, there is a problem that surfaces of teeth that have been whitened by a bleaching chemical, such as hydrogen peroxide, urea peroxide, etc., become covered with pellicles and plaque in a short time and return of color occurs at an early stage.
On the other hand, the present inventors have already developed a biocompatible ceramic film having flexibility and pliability that is useable for tissue grafting, cell observation, etc., of skin, etc. (see Patent Document 4).